RSVPhase 2/3RESOLVENCT07908381
A Study to Investigate the Efficacy and Safety of Zelicapavir Compared With Placebo in Adults With RSV Who Are at High Risk for Severe Disease
A Phase 2/3 study testing zelicapavir in people with RSV, run by Enanta Pharmaceuticals, Inc at 4 sites in United States.
Trial summary
Zelicapavir is a novel orally administered non-fusion replication inhibitor of RSV that is being developed for the treatment of patients with RSV infection. This phase 2b/3 study will evaluate the efficacy and safety of zelicapavir compared with placebo in adults with RSV who are at high risk for severe disease. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- RSV
- What is being tested?
- zelicapavir
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 860 participants
- Where
- 4 sitesUnited States
- Study dates
- 19 Oct 2026to Jul 2029
- Phase
- Phase 2/3
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Age ≥75 years at the time of enrollment, or, age ≥18 at the time of enrollment and has at least one of the following conditions that predispose them to complications of RSV infection:
- CHF
- COPD
- New onset or worsening of preexisting symptoms consistent with respiratory tract infection no more than 72 hours before administration of the first dose of study intervention: feeling feverish, headache, neck pain, fatigue, loss of appetite, interrupted sleep, body aches, sore throat, nasal congestion, cough, cough with phlegm, wheezing, or short of breath.
- Reports at least 2 of the following symptoms, one of which must be reported by the participant as at least moderate in severity using the RiiQ™: cough, cough with phlegm, wheezing, or short of breath.
- Tested positive for RSV infection defined as a positive nucleic acid amplification test (PCR or other) or rapid-antigen viral detection test performed on a nasal swab specimen collected no more than 72 hours before administration of the first dose of study intervention.
- A woman of childbearing potential who is sexually active with a male must agree to use two effective methods of contraception from the date of Screening until 30 days after her last dose of study drug.
- A male subject who has not had a vasectomy and is sexually active with a woman of childbearing potential must agree to use effective contraception from the date of Screening to 90 days after his last dose of study drug.
Who cannot join
- Reported history of respiratory infection (other than RSV) within 7 days prior to signing the ICF.
- Anticipated need for hospitalization within 24 hours of signing the ICF.
- Receiving dialysis or have known severe renal impairment.
- Reported history of chronic liver disease, including cirrhosis, autoimmune hepatitis, end stage liver disease, history of hepatocellular carcinoma, or decompensated liver failure.
- Prior receipt of or waiting to receive a bone marrow, stem cell, or solid organ transplant. Currently taking, or has taken within 7 days prior to randomization, or is anticipated to receive during the study, systemic medications that are known to cause immunosuppression. Note: Chronic use of immunomodulators such as dupilumab and omalizumab is permitted.
Trial locations and contacts
4 sites in 1 country. Contact the study team or a site near you to ask about taking part.
United States4 sites, 4 recruiting
- Recruiting
PanAmerican Clinical Research
Bluffton, South Carolina, 29910
- Recruiting
PanAmerican Clinical Research - Brownville
Brownsville, Texas, 78520
- Recruiting
C&A Clinical Trials Corp
Cape Coral, Florida, 33990
- Recruiting
Continental Clinical Research, LLC
Miami, Florida, 33144
About this study
Official title: A Randomized, Double-blind, Placebo-controlled, Phase 2b/3 Study to Evaluate the Efficacy and Safety of Zelicapavir for Respiratory Syncytial Virus Infection in Adults Who Are at High Risk for Severe Disease
Zelicapavir is a novel orally administered non-fusion replication inhibitor of RSV that is being developed for the treatment of patients with RSV infection. This phase 2b/3 study will evaluate the efficacy and safety of zelicapavir compared with placebo in adults with RSV who are at high risk for severe disease. High-risk participants include those who are either ≥75 years of age or ≥18 years of age with COPD and/or CHF. Participants will be non-hospitalized adults who have up to 72 hours of respiratory tract infection symptoms and test positive for RSV.
- Conditions
- RSV
- Being tested
- zelicapavir, Placebo
- Keywords
- High Risk, Respiratory Syncytial Virus, EDP-938, COPD, CHF, Elderly
- Medical subject headings
- Pulmonary Disease, Chronic Obstructive
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
zelicapavirDrug
Zelicapavir 800mg, once daily for 7 days
PlaceboDrug
Participants will take matching placebo, once daily for 7 days
| Study group | Role | What they receive |
|---|---|---|
| zelicapavir | Experimental | Zelicapavir 800 mg, orally Receives: Drug: zelicapavir |
| Placebo | Placebo comparator | Matching placebo, orally Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Time to complete resolution of all 13 RSV symptoms as assessed by the Respiratory Infection Intensity and Impact Questionnaire (RiiQ) symptom scale
Measured: Day 1 through Day 21
Secondary outcomes (19)
Number of participants with hospitalization due to RSV
Measured: Day 1 through Day 35
Number of participants with hospitalization or death due to any cause
Measured: Day 1 through Day 35
Number of participants who died
Measured: Day 1 through Day 35
Number of participants with non-protocol defined medical visits for any cause
Measured: Day 1 through Day 35
Time to complete resolution of RSV LRTD symptoms by RiiQ
Measured: Day 1 through Day 21
Time to complete resolution of all 29 RSV parameters as assessed by RiiQ symptom scale score
Measured: Day 1 through Day 21
Time to alleviation of LRTD symptoms by RiiQ
Measured: Day 1 through Day 21
Time to alleviation of all 13 RSV symptoms as assessed by RiiQ
Measured: Day 1 through day 21
Time to alleviation of all 29 RSV parameters as assessed by RiiQ
Measured: Day 1 through Day 21
Time to complete resolution of RSV infection symptoms as assessed by PGI-S scale
Measured: Day 1 through Day 35
Time to resolution to pre-existing symptoms
Measured: Day 1 through Day 21
Number of participants requiring mechanical ventilation
Measured: Day 1 through Day 35
Number of participants requiring supplemental oxygen in hospital
Measured: Day 1 through Day 35
Number of participants requiring ICU admission
Measured: Day 1 through Day 35
Change from baseline in RSV viral load
Measured: Up to Day 35
Percentage of participants with RSV RNA viral load TND
Measured: Up to Day 35
Time to RSV RNA viral load TND
Measured: Up to Day 35
Safety as measured by frequency of adverse events (AEs)
Measured: Day 1 through Day 35
Plasma Concentrations of zelicapavir
Measured: At Day 7
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Nov 2026
- Study start19 Oct 2026
- Primary completionJul 2029 (estimated)
- Study completionJul 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for RSVStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2/3
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind
- Who is masked
- Participant, Care provider, Investigator
- Enrolment
- 860 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Enanta Pharmaceuticals, Inc
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Enanta Pharmaceuticals, Inc, Study director, Enanta Pharmaceuticals, Inc
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07908381
- Sponsor's protocol ID
- EDP 938-105
- Other IDs
- 2026-527282-30-00
- Acronym
- RESOLVE
- Status last verified
- Oct 2026
- First submitted
- 26 Oct 2026
- Last updated
- 2 Nov 2026
- Results posted
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 2 Nov 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Randomized, Double-blind, Placebo-controlled, Phase 2b/3 Study to Evaluate the Efficacy and Safety of Zelicapavir for Respiratory Syncytial Virus Infection in Adults Who Are at High Risk for Severe Disease
- ClinicalTrials.gov ID
- NCT07908381
- Acronym / sponsor ID
- RESOLVE / EDP 938-105
- Conditions
- RSV
- Keywords
- High Risk, Respiratory Syncytial Virus, EDP-938, COPD, CHF, Elderly
- Phase
- Phase 2/3
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 860 participants (estimated)
- Lead sponsor
- Enanta Pharmaceuticals, IncIndustry (pharma, biotech, devices)
- Study start
- 19 Oct 2026 (actual)
- Primary completion
- Jul 2029 (estimated)
- Study completion
- Jul 2029 (estimated)
- First posted
- 2 Nov 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Zelicapavir is a novel orally administered non-fusion replication inhibitor of RSV that is being developed for the treatment of patients with RSV infection. This phase 2b/3 study will evaluate the efficacy and safety of zelicapavir compared with placebo in adults with RSV who are at high risk for severe disease. High-risk participants include those who are either ≥75 years of age or ≥18 years of age with COPD and/or CHF. Participants will be non-hospitalized adults who have up to 72 hours of respiratory tract infection symptoms and test positive for RSV.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind (participant, care provider, investigator)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| zelicapavir | Experimental | Drug: zelicapavirZelicapavir 800 mg, orally |
| Placebo | Placebo comparator | Drug: PlaceboMatching placebo, orally |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (8 listed)
- Age ≥75 years at the time of enrollment, or, age ≥18 at the time of enrollment and has at least one of the following conditions that predispose them to complications of RSV infection:
- New onset or worsening of preexisting symptoms consistent with respiratory tract infection no more than 72 hours before administration of the first dose of study intervention: feeling feverish, headache, neck pain, fatigue, loss of appetite, interrupted sleep, body aches, sore throat, nasal congestion, cough, cough with phlegm, wheezing, or short of breath.
- Reports at least 2 of the following symptoms, one of which must be reported by the participant as at least moderate in severity using the RiiQ™: cough, cough with phlegm, wheezing, or short of breath.
- Tested positive for RSV infection defined as a positive nucleic acid amplification test (PCR or other) or rapid-antigen viral detection test performed on a nasal swab specimen collected no more than 72 hours before administration of the first dose of study intervention.
- A woman of childbearing potential who is sexually active with a male must agree to use two effective methods of contraception from the date of Screening until 30 days after her last dose of study drug.
Key exclusion criteria (5 listed)
- Reported history of respiratory infection (other than RSV) within 7 days prior to signing the ICF.
- Anticipated need for hospitalization within 24 hours of signing the ICF.
- Receiving dialysis or have known severe renal impairment.
- Reported history of chronic liver disease, including cirrhosis, autoimmune hepatitis, end stage liver disease, history of hepatocellular carcinoma, or decompensated liver failure.
- Prior receipt of or waiting to receive a bone marrow, stem cell, or solid organ transplant. Currently taking, or has taken within 7 days prior to randomization, or is anticipated to receive during the study, systemic medications that are known to cause immunosuppression. Note: Chronic use of immunomodulators such as dupilumab and omalizumab is permitted.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| zelicapavirZelicapavir 800mg, once daily for 7 days | Drug | zelicapavir |
| PlaceboParticipants will take matching placebo, once daily for 7 days | Drug | Placebo |
Primary outcome
Time to complete resolution of all 13 RSV symptoms as assessed by the Respiratory Infection Intensity and Impact Questionnaire (RiiQ) symptom scale
Time frame: Day 1 through Day 21
19 secondary outcomes
Number of participants with hospitalization due to RSV
Time frame: Day 1 through Day 35
Number of participants with hospitalization or death due to any cause
Time frame: Day 1 through Day 35
Number of participants who died
Time frame: Day 1 through Day 35
Number of participants with non-protocol defined medical visits for any cause
Time frame: Day 1 through Day 35
Time to complete resolution of RSV LRTD symptoms by RiiQ
Time frame: Day 1 through Day 21
Time to complete resolution of all 29 RSV parameters as assessed by RiiQ symptom scale score
Time frame: Day 1 through Day 21
Time to alleviation of LRTD symptoms by RiiQ
Time frame: Day 1 through Day 21
Time to alleviation of all 13 RSV symptoms as assessed by RiiQ
Time frame: Day 1 through day 21
Time to alleviation of all 29 RSV parameters as assessed by RiiQ
Time frame: Day 1 through Day 21
Time to complete resolution of RSV infection symptoms as assessed by PGI-S scale
Time frame: Day 1 through Day 35
Time to resolution to pre-existing symptoms
Time frame: Day 1 through Day 21
Number of participants requiring mechanical ventilation
Time frame: Day 1 through Day 35
Number of participants requiring supplemental oxygen in hospital
Time frame: Day 1 through Day 35
Number of participants requiring ICU admission
Time frame: Day 1 through Day 35
Change from baseline in RSV viral load
Time frame: Up to Day 35
Percentage of participants with RSV RNA viral load TND
Time frame: Up to Day 35
Time to RSV RNA viral load TND
Time frame: Up to Day 35
Safety as measured by frequency of adverse events (AEs)
Time frame: Day 1 through Day 35
Plasma Concentrations of zelicapavir
Time frame: At Day 7
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 2 Nov 2026.
Related trials for RSV
RecruitingPhase 3
Study to Learn About a Respiratory Syncytial Virus Vaccine in Children at High Risk of RSV Disease
Respiratory Syncytial Virus (RSV)
Active, not recruitingPhase 3
A Study on the Immune Response and Safety of Vaccine Against Respiratory Syncytial Virus Given to Chinese Adults 18 to 59 Years of Age at Increased Risk of Respiratory Syncytial Virus Disease
Respiratory Syncytial Virus Infections
Active, not recruitingPhase 1
A Phase 1 Study to Evaluate JCXH-108, an mRNA-based Vaccine Against RSV
Respiratory Syncytial Virus (RSV), Infectious Disease
RecruitingPhase 2
Immunogenicity of RSVPreF3 Vaccine in Immunocompromised Persons
Respiratory Syncytial Virus (RSV)
RecruitingObservational study
TARSILA Real-World Evidence Study
Respiratory Syncytial Virus (RSV), Maternal Immunization
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Enanta Pharmaceuticals, Inc study director
Enanta Pharmaceuticals, Inc
4 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2/3 study testing zelicapavir in people with RSV, run by Enanta Pharmaceuticals, Inc at 4 sites in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 8 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 2 Nov 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 4 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this combined phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Chris Harris, MD (617-607-0800, charris@enanta.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Time to complete resolution of all 13 RSV symptoms as assessed by the Respiratory Infection Intensity and Impact Questionnaire (RiiQ) symptom scale (time frame: Day 1 through Day 21). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 2 Nov 2026.